POS1118 DISCRIMINATING CAPACITY OF THE ASAS HEALTH INDEX IN PATIENTS TREATED WITH IXEKIZUMAB IN THE COAST PROGRAMME
Authors: U. Kiltz, A. Moltó, D. Van der Heijde, L. Bessette, A. Boonen, R. Bolce, C. Sapin, T. Hunter, B. Janos, A. Kronbergs, S. Liu Leage, J. Braun
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> The Assessment of SpondyloArthritis international Society Health Index (ASAS HI) is a validated health outcome measure used to assess functioning and health in patients (pts) with axial spondyloarthritis (axSpA) [1]. Two thresholds for clinical improvement have been recently proposed: improvement ≥3 points and a 30% improvement from baseline [1,2]. However, an exploration of the optimal threshold in an independent cohort has not been carried out to date. <h3>Objectives</h3> Using data from the COAST trials, this analysis aimed to test the discriminatory capacity of the ASAS HI at different thresholds of improvement. <h3>Methods</h3> This <i>post hoc</i> analysis included patients treated with either ixekizumab (IXE) 80 mg every 4 weeks (Q4W) or placebo (PBO) from the intent-to-treat populations of COAST-V (NCT02696785) and COAST-W (NCT02696798) for radiographic (r)-axSpA, and COAST-X (NCT02757352) for non-radiographic (nr)-axSpA over 16 weeks. To assess the discriminatory capacity of the ASAS HI, response rates at Week 16 were compared between IXE Q4W and PBO using Fisher's exact test. Phi coefficients (ranging from -1 to +1) were calculated to compare the degree of association between the level of improvement and treatment allocation. Missing data were handled using non-responder imputation. <h3>Results</h3> ASAS HI data at Week 16 were available for pts with r-axSpA from COAST-V (IXE Q4W, N=81; PBO, N=87) and COAST-W (IXE Q4W, N=114; PBO, N=104) and pts with nr-axSpA from COAST-X (IXE Q4W, N=96; PBO, N=105). Percentages of pts reaching improvement scores for different study arms are shown in Figure 1. Differences in response rates by the various absolute or relative thresholds for improvement are shown in Table 1. Data demonstrated an inconsistent picture of the best performing threshold between the different COAST studies. While for COAST-V discriminatory capacity were demonstrated for higher values this was opposite to COAST-W, and there was no clear discriminating threshold in COAST-X (Table 1, Figure 1). The majority of Phi coefficients were below 0.2, suggestive of low discriminatory capacity. <h3>Conclusion</h3> In this post hoc analysis of pts from the COAST trials at Week 16, several thresholds of improvement of the ASAS HI seem to have discriminating capacity. However, there were some differences between the COAST trials and no single threshold worked best in the r-axSpA (bDMARD-naïve and experienced) and nr-axSpA populations. <h3>References</h3> [1]Kiltz, U., <i>et al.</i> Ann Rheum Dis. 2018;77 [2]Molto A., <i>et al</i>. Ann Rheum Dis. 2021 Nov;80(11) <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Uta Kiltz Speakers bureau: AbbVie, Biocad, Chugai, Eli Lilly and Company, Fresenius, Grünenthal, Hexal, Janssen, MSD, Novartis, Pfizer, Roche, UCB, Consultant of: AbbVie, Biocad, Chugai, Eli Lilly and Company, Grünenthal, Janssen, MSD, Novartis, Pfizer, Roche, UCB, Grant/research support from: AbbVie, Amgen, Biogen, Fresenius, GSK, Hexal, Novartis, Pfizer, Anna Moltó Consultant of: Abbvie, Biogen, BMS, Gilead, Eli Lilly and Company, MSD, Novartis, Pfizer, UCB, Grant/research support from: UCB, Pfizer, Désirée van der Heijde Speakers bureau: AbbVie, Amgen, Astellas, AstraZeneca, Bayer, BMS, Boehringer Ingelheim, Celgene, Cyxone, Daiichi, Eisai, Eli Lilly and Company, Galapagos, Gilead, GSK, Janssen, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi, Takeda, and UCB Pharma, Consultant of: AbbVie, Amgen, Astellas, AstraZeneca, Bayer, BMS, Boehringer Ingelheim, Celgene, Cyxone, Daiichi, Eisai, Eli Lilly and Company, Galapagos, Gilead, GSK, Janssen, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi, Takeda, and UCB Pharma, Louis Bessette Speakers bureau: Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Merck, Eli Lilly and Company, Novartis, Sanofi, Sandoz, Fresenius Kabi, Teva, Organon, JAMP Pharma, Consultant of: Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Merck, Eli Lilly and Company, Novartis, Sanofi, Sandoz, Fresenius Kabi, Teva, Organon, JAMP Pharma, Grant/research support from: Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Merck, Celgene, Sanofi, Eli Lilly and Company, Novartis, Gilead, JAMP Pharma, Annelies Boonen Speakers bureau: Eli Lilly and Company, Novartis, Abbvie, Consultant of: Galapagos, Grant/research support from: AbbVie, Rebecca Bolce Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Christophe Sapin Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Theresa Hunter Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Boris Janos Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Andris Kronbergs Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Soyi Liu Leage Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Juergen Braun Consultant of: AbbVie, Amgen, Celgene, Eli Lilly and Company, Janssen, MSD, Novartis, Pfizer, Sanofi, and UCB.